Bull. Jpn. Soc. Fish. Oceanogr. 77(2), Page 83-91, 2013   Influence of Tsushima Warm Current on the fishing ground formation of swordtip squid （Photololigo edulis） in the Sea of Genkai, Japan Akihiko Ando1, Hideaki Nakata2 and Joji Ishizaka3 1 Graduate School of Science and Technology, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, Nagasaki 852-8521, Japan E-mail: a-ando@siren.ocn.ne.jp 2 Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, Nagasaki 852-8521, Japan E-mail: nakata@nagasaki-u.ac.jp 3 Hydrospheric Atmospheric Research Center, Nagoya University, 1 Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan † E-mail: jishizak@hyarc.nagoya-u.ac.jp In order to examine the effect of the Tsushima Warm Current on the swordtip squid Photololigo edulis fishery in the Sea of Genkai, we analyzed the operation record by squid fishing boats and satellite sea surface temperature （SST） in April and November from 2000 to 2005. The swordtip squid was fished in the area of limited range of SST during each month; however, the SST of the fishing ground in April was quite different from that in November. The distribution of fishing positions weighted-averaged by daily catch was classified into concentrated or dispersed patterns in April. On the other hand, the distribution of the fishing positions in November only had a concentrated pattern. Inflow of the Tsushima Warm Current into the Sea of Genkai in April was also classified into offshore or inshore patterns, judging from monthly satellite SST; however, it was not clearly consistent with the distribution patterns of the fishing positions. It was revealed that because the above temperature range in April was suitable for spawning of the swordtip squid, the fishing ground was concentrated into a narrow zone in the years when the area with the suitable water temperature was limited to the narrow zone, depending on the inflow of the Tsushima Warm Current. In the years when the area suitable for spawning was widely distributed, the fishing ground was dispersed. The fishing ground in November was mainly formed off Okinoshima and not related to the temperature suitable for spawning. These results indicated that inflow of the Tsushima Warm Current to the Sea of Genkai could have strong influence on the fishing ground formation of the swordtip squid through the temperature condition, particularly in its spawning season. Key words: satellite, sea surface temperature, swordtip squid, Tsushima Warm Current, fishing ground